Add frontend listing products and admin resource

Add simple 'frontend' #index and #show for products and a 'backend'
with basic CRUD operations.

Add simple - initial - structure for tests.

Update Gemfile removing unused gems (rspec) and adding sqlite3 as
development dependency.

Squashed commit of the following:

commit 10809dd1da8ebe6ccbe4170f2738b3e493294166
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 07:22:25 2013 -0200

    Add on admin namespace a resource for products

commit d8210b2d16d5f2dde10c8d707d80769941117c25
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 07:21:50 2013 -0200

    Add assertion for forms to keep assert_select simple

commit 229ece3924f56962278677cc27c9e36f7407c4a7
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 05:18:13 2013 -0200

    Add basic products resource, with just #index and #show for front end

commit 074e3ab2881ee2dc5132ed2121da99eb1c1f0a9a
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 05:17:29 2013 -0200

    Review layout to use content_for(:title) at 'head title'

commit 01dfca08535d15c6c8dd5c11971b6ed75fb02c84
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 05:16:50 2013 -0200

    Add assertion for action title

commit df3dc39737649847c31816cc90ddcbfd4cb1764a
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 05:16:30 2013 -0200

    Add #action_title helper

commit c6847342249e81fda2806c7df260fd055458f62c
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 03:47:55 2013 -0200

    Trivia: gitignore for backup files and remove some .gitkeep files

commit e06e664b5f01f667dd5a01007f5dfa3ec47a0526
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 03:42:58 2013 -0200

    Add products model

commit a40c83f351d6a9ead1a8835b183181f77adc333e
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Sat Feb 16 03:24:04 2013 -0200

    Add migration for Products model

commit 81640b71cb46798df6e75f85edf1c09e68f04f98
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Fri Feb 15 18:58:21 2013 -0200

    Change database config to use Sqlite3 for development and test

commit b7b9fd192a5436146ecdf6f9783928701135a063
Author: Everton J. Carpes <everton.carpes@gmail.com>
Date:   Fri Feb 15 18:55:25 2013 -0200

    Update Gemfile to use Sqlite3 as development database and remove rspec